Cigarette Filter

ABSTRACT

[Problem to be Solved] To provide a cigarette filter capable of very effectively adsorbing/eliminating carcinogens such as dioxins and benzpyrene in mainstream smoke generated in cigarette smoking, and maintaining the flavor characteristic of cigarette and air permeability of cigarette filter. 
     [Solution] Provided is a cigarette filter containing a harmful substance-eliminating material comprising a double-stranded DNA and/or a corn cob powder.

TECHNICAL FIELD

The present invention relates to a cigarette filter containing a harmful substance-eliminating material comprising DNA and/or a corn cob powder capable of effectively eliminating harmful substances in mainstream smoke of cigarettes in smoking, and less deteriorating the flavor characteristic of cigarette and air permeability of filter.

BACKGROUND ART

Conventionally, as cigarette filters, cellulosic compounds have generally been used. For example, a filter consisting of cellulose acetate fiber has been widely used because it does not deteriorate flavor in smoking, and can adsorb and eliminate harmful components in mainstream smoke of cigarettes. Specifically, for example, filtration efficiency of filter is improved in such manner that cellulose acetate fibers are processed into a crimped tow, and the fineness of single fiber in this tow is decreased, or the filled amount of fibers is increased. Further, in order to improve adsorptive property of harmful components, it is known that inorganic adsorbents such as active carbon and zeolite are added to the above-described cigarette filters, as a typical example, the followings can be listed:

(1) one containing zeolite powder as an adsorbent (Patent document 1). (2) one containing a porous glass composed of at least CaO, B₂O₃, SiO₂ and AlO₃ (Patent document 2).

Further, in addition to the above-described inorganic adsorbents, it is also known that DNA as an active component is directly attached onto a filter, by which carcinogenic toxic products contained in cigarette smoke are trapped (Patent document 3).

On the other hand, as a material for adsorbing/eliminating harmful components, as an example, known are soil, sand, gravel, clay, stone, concrete, asphalt, brick, block, carbon such as active carbon and carbon black, zeolite, polymer, plastic, elastomer material, metal, metal alloy such as steel, glass, glass fiber, ceramic, textiles such as cloth and knit, cellulosic material, and combinations thereof.

Among these, as a specific cellulosic material, there are known wood, wood chip, sawdust, paper, cardboard, and corn cob powder (corn cob).

-   Patent document 1: Japanese Patent Application Laid-open No. Hei     02-308784 -   Patent document 2: Japanese Patent Application Laid-open No.     2001-95552 -   Patent document 3: French patent No. 2798302

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

Incidentally in recent years, harmful substances in mainstream smoke of cigarettes, particularly regarding dioxins and benzpyrene, attention is paid to the carcinogenicity, there have been increasing demands to desire a filter capable of effectively adsorbing/eliminating these harmful substances. However, in regard to the cigarette filter that the harmful substance adsorbing/eliminating capability is improved by addition of the above-described inorganic adsorbent, although a removal effect of tar and nicotine in mainstream smoke of cigarettes is mentioned, a removal effect of dioxins and benzpyrene has not been shown.

Further, there has been a case that a cigarette filter capable of eliminating harmful substances in mainstream smoke of cigarettes has not only the harmful substance eliminating capability but eliminates flavor characteristic of cigarette, namely, a chemical substance as the original flavor as well, or adds flavor of material used in the filter, which deteriorates the flavor of cigarette. Further, there may be a case that air permeability of filter is deteriorated, resulting in resistance to suction of cigarette smoke, which leads to quality loss of cigarette, thus care should be exercised in these points.

The present inventors have keenly studied to solve the above-described problem in the conventional techniques, as a result, unexpectedly found the following: using a corn cob powder on which DNA is attached as a harmful substance eliminating substance, by having the harmful substance-eliminating material contained in a cigarette filter, harmful substances in mainstream smoke of cigarettes can be adsorbed/eliminated more effectively than, not to mention, the case where a conventional active carbon or the like is contained in a cigarette filter, and, also, than the case where only corn cob powder or only DNA is contained in a cigarette filter; moreover, the flavor characteristic of cigarette and excellent air-permeability of filter can be maintained, and completed the present invention.

Namely, the present invention aims to provide a cigarette filter capable of very effectively adsorbing carcinogens such as dioxins and benzpyrene and maintaining the flavor characteristic of cigarette and air permeability of filter.

Means to Solve the Problem

The present invention relates to a cigarette filter containing a harmful substance-eliminating material comprising a double-stranded DNA and/or a corn cob powder.

In the cigarette filter of the present invention, it is preferable that the double-stranded DNA contained in the harmful substance-eliminating material is attached onto the surface of the corn cob powder.

Further, it is preferable that the corn cob powder contained in said harmful substance-eliminating material is a corn cob powder which is dried to contain a water content of 5 mass % or less.

Further, said harmful substance-eliminating material is mixed in a filter rod consisting of a fibrous filter material to result in the cigarette filter of the present invention, in this case, preferably, the harmful substance-eliminating material may comprise a double-stranded DNA and/or a corn cob powder having a particle diameter of 150 μm to 500 μm.

Alternatively, a plurality of filter rods consisting of a fibrous filter material are provided, and a layer composed of said harmful substance-eliminating material is interposed between said filter rods to result in the cigarette filter of the present invention, in this case, preferably, the harmful substance-eliminating material may comprise a double-stranded DNA and/or a corn cob powder having a particle diameter of 500 μm to 1000 μm.

Further, as the harmful substance eliminated by the cigarette filter of the present invention, it may be dioxins or/and benzpyrene.

EFFECT OF THE INVENTION

According to the present invention, as a harmful substance-eliminating material, by the constitution that a double-stranded DNA is attached onto the surface of corn cob powder, harmful substances in cigarette smoking, particularly, dioxins, benzpyrene and the like are trapped by intercalation between the double-stranded DNA molecules, at the same time, the harmful substances can also be adsorbed by a porous structure which the corn cob powder has, thereby it becomes possible to eliminate the harmful substances in mainstream smoke effectively. Further, by the above-described constitution, namely, by attaching a double-stranded DNA onto the surface of corn cob powder, the double-stranded DNA is hardly dropped in comparison with the direct attachment of the double-stranded DNA onto a cigarette filter (fibrous filter material), giving a merit that the harmful substance eliminating capability can be kept for a long time.

Further, by adjusting the attached amount of the double-stranded DNA onto the corn cob powder, the particle diameter and used amount of the corn cob powder, it is possible to maintain the flavor characteristic of cigarette and excellent air-permeability of filter at the same time while having the above-described harmful substance eliminating capability.

In addition, corn cob powders are usually treated as an industrial waste in agricultural regions, so that one kind of harmful substance-eliminating materials can be cheaply procured.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, each constituent element and its function of the cigarette filter of the present invention will be further described.

(1) Double-Stranded DNA

The double-stranded DNA contained in the harmful substance-eliminating material of the present invention consists of two polynucleotide chains of a helical form (double helix), for example, it is preferably DNA obtained from milt (testis) of fish such as salmon, sardine and cod, or DNA obtained from thymus of mammals or birds such as cow, pig and chicken.

Double-stranded DNA is bonded by hydrogen bond in such manner that both planar bases having a structural complementation protrude toward the central part of helix being vertical to the axis of helix from sugar-phosphoric acid skeleton of two polynucleotide chains. Between pairs of the bases of two chains of DNA, in the case of B type structure, there is a gap of about 1.1 nm wide and 0.34 nm high, a small molecule having a planar structure can penetrate in this gap, which is called “intercalation.” There is a case where this phenomenon is accelerated by an electric charge or hydrophobicity of a small molecule. Harmful substances to human such as dioxins are often composed of a plurality of benzene rings, and these have a planar structure. Therefore, by utilizing the double-stranded DNA, it is possible to trap/eliminate harmful substances generated from mainstream smoke of cigarettes in smoking.

As a form of the double-stranded DNA, the one which can be attached onto the external surface of corn cob powder may be enough, for example, it may be a powder-like, fiber-like or film-like form, preferably a powder-like, in particular, preferably a fine powder-like form. By making the double-stranded DNA into a fine powder-like form, the total surface area of the double-stranded DNA becomes relatively large, which can further improve the harmful substance trapping/eliminating capability.

(2) Corn Cob Powder

The corn cob powder contained in the harmful substance-eliminating material of the present invention is the one obtained by grinding a corn cob part, preferably the one obtained by grinding a corn cob part. Preferably, the one obtained by grinding after a corn cob part is dried in the sun or by a dryer is mentioned.

The shape of the corn cob powder is not particularly limited, and it may be various shapes obtained by grinding (for example, polyhedron such as tetrahedron, hexahedron and octahedron, sphere, flat sphere or the like). Additionally, it is known that the internal structure of the corn cob powder is porous and shows a honeycomb structure (comb of bees) and further has a number of small holes in the faces of dividing walls forming a hole (by Seiki Ishigouoka et. al, lecture summary at general convention of Japanese Association for Experimental Animal Technologists), and it is assumed that harmful substances are adsorbed in such small holes. Namely, the harmful substance eliminating capacity of corn cob powder is thought to be resulted from the internal structure that it has in itself.

The particle diameter of the corn cob powder is considered and suitably chosen so that the powder can be mixed in a filter rod consisting of a fibrous filter material, or a layer composed of a harmful substance-eliminating material can be interposed between a plurality of filter rods consisting of the fibrous filter material and can have an effective harmful substance eliminating capability and also maintain the flavor of cigarette and an excellent air-permeability of cigarette filter. When the particle diameter is too large, the total surface area of powder becomes relatively small, a target amount of the foregoing double-stranded DNA sometimes cannot be attached, which leads to be inferior relatively in the point of harmful substance eliminating capability, further, it may become difficult to mix in a filter rod consisting of the fibrous filter material, and reversely when the particle diameter is too small, although the attached amount of double-stranded DNA and the harmful substance eliminating capability are kept in a high level, air permeability of the whole filter is lowered, and clogging of a fibrous filter material tends to be caused. Therefore, in the case where the powder is mixed in a filter rod consisting of the fibrous filter material, the particle diameter is preferably in a range of 150 μm to 500 μm. Further, in the case of being interposed between the filter rods as a layer composed of corn cob powder, the particle diameter is preferably in a range of 500 μm to 1000 μm.

Further, the corn cob powder is preferably in a dried state, and the water content is preferably 5 mass % or less.

(3) Method for Producing Harmful Substance-Eliminating Material

The harmful substance-eliminating material of the present invention is preferably the one that a double-stranded DNA is attached on the surface of corn cob powder, in this case, the double-stranded DNA can be attached by spraying it onto the corn cob powder. In this case, the double-stranded DNA can be attached on the corn cob powder by a physical force, for example, an intermolecular force, an electrostatic force, or chemical bonds such as covalent bond, ion bond and coordinated bond, or both bonds thereof. Additionally, in the present invention, as long as a double-stranded DNA is present in a state being not dropped from a corn cob powder, it is deemed that the double-stranded DNA is attached onto the corn cob powder.

(4) Method for Setting a Harmful Substance-Eliminating Material in Cigarette Filter

The harmful substance-eliminating material of the present invention may be mixed in a filter rod consisting of a fibrous filter material, or a layer composed of a harmful substance-eliminating material is formed, and the layer may be interposed between a plurality of filter rods consisting of the fibrous filter material.

In the case where the harmful substance-eliminating material is mixed in a filter rod consisting of the fibrous filter material, regarding the distribution of the harmful substance-eliminating material in the filter rod, from consideration of exhibition of effective adsorbing/eliminating effect on harmful substances, it is preferably distributed partially in one terminal side contacting cigarette in a cigarette filter.

Further, in the case where a layer composed of a harmful substance-eliminating material is formed, and the layer is interposed between a plurality of filter rods consisting of the fibrous filter material, namely, in the case of a sandwich structure that the layer is sandwiched with the fibrous filter materials, from consideration of exhibition of effective adsorbing/eliminating effect on harmful substances, it is preferable to interpose the layer near the central part of a cigarette filter.

(5) Amount of Harmful Substance-Eliminating Material (Double-Stranded DNA and/or Corn Cob Powder)

The used amount of the harmful substance-eliminating material of the present invention, namely the used amount of the double-stranded DNA and/or the corn cob powder is considered and suitably chosen so that a harmful substance eliminating capability is effectively obtained in processing into a cigarette filter and can maintain the flavor of cigarette and excellent air-permeability of cigarette filter.

When the used amount of the double-stranded DNA and/or the corn cob powder is too small, there is a case that a target harmful substance eliminating capability cannot be achieved, whereas when too large, air permeability of filter may be deteriorated because the filter is clogged.

Therefore, for example, in the case where it is mixed in a filter rod consisting of the fibrous filter material, the double-stranded DNA is used in a range of 0.001 mass % to 0.1 mass % relative to the filter rod, preferably in a range of 0.002 mass % to 0.05 mass %, and more preferably in a range of 0.005 mass % to 0.01 mass %, and the corn cob powder is used in a range of 0.05 mass % to 10 mass %, preferably in a range of 0.1 mass % to 5 mass %, and more preferably in a range of 0.3 mass % to 1 mass %.

Further, in the case where a layer composed of a harmful substance-eliminating material is formed, and the layer is interposed between a plurality of filter rods consisting of the fibrous filter material, the double-stranded DNA is used in a range of 0.0001 mass % to 0.1 mass % relative to the filter rod, preferably in a range of 0.001 mass % to 0.05 mass %, and more preferably in a range of 0.003 mass % to 0.01 mass %, and the corn cob powder is used in a range of 0.01 mass % to 10 mass %, preferably in a range of 0.05 mass % to 3 mass %, and more preferably in a range of 0.1 mass % to 1.5 mass %.

(6) Fibrous Filter Material

As raw materials of the fibrous filter material in the present invention, a raw material commonly used for a cigarette filter may be used, for example, there may be cellulose fiber, cellulose ester fiber, for example, organic acid ester such as cellulose acetate, cellulose propionate and cellulose butyrate; mixed acid ester such as cellulose acetate propionate and cellulose acetate butyrate; and cellulose ester derivatives such as polycaprolactone-grafted cellulose ester. These may be used alone, or in combination of 2 kinds or more thereof.

(7) Other Contained Material

The cigarette filter of the present invention may also contain a material capable of further eliminating harmful substances, for example, active carbon, fragrances or the like, as long as the harmful substance eliminating capability of the double-stranded DNA and/or corn cob powder is not deteriorated, and the flavor of cigarette and excellent air-permeability are maintained.

EXAMPLES

Next, the present invention will be described further specifically with reference to Examples. It should not be construed under any circumstances that the following Examples restrict the present invention.

In the present Examples and Comparative examples, four kinds of cigarettes for test were prepared by using four kinds of cigarette filters prepared according to the procedure described below, and elimination effects on various kinds of harmful substances in mainstream smoke of cigarettes, and smoking tests on smoking feeling were carried out.

<Preparation of Cigarette Filter for Test> Example 1

Onto about 100 g of corn cob powder (manufactured by Rengo Co., Ltd., particle diameter of 0.6 mm or more), 1.5 g of double-stranded DNA of fine powder form was sprayed and attached (DNA concentration: 1.5 mass %). Subsequently, using two pieces of acetate filter commercially available (0.8 cm width in longitudinal direction), a granular layer (about 0.5 cm width) composed of the corn cob powder that the DNA was attached in 114 mg/piece was sandwiched with the filters to obtain a cigarette filter for test.

Comparative Example 1

In the present Comparative example, a cigarette filter for test was obtained in the same manner as in Example 1 except that only the corn cob powder used in Example 1 was used as a granular layer.

Comparative Example 2

In the present Comparative example, a cigarette filter for test was obtained in the same manner as in Example 1 except that a granular layer was composed by using an active carbon (manufactured by Senetin Corporation (Korea), particle diameter of 0.51 mm or more) in 189 mg/piece.

Comparative Example 3

In the present Comparative example, a cigarette filter for test was obtained by using only an acetate filter commercially available (2.1 cm width in longitudinal direction).

<Preparation of Cigarette for Test>

The cigarette filters for test prepared in Example 1 and Comparative examples 1 to 3 were stored under the atmosphere of relative humidity at 60% and temperature at 22° C. for 48 hours and more.

As a cigarette part, a commercially available cigarette (manufactured by JT Corporation, product name: Seven Star) was used, the cigarette part was also stored under the atmosphere of relative humidity at 60% and temperature at 22° C. for 48 hours and more, and it was connected with the cigarette filter for test just before the start of smoking test to give a cigarette for test.

The cigarette for test obtained was examined each according to the test methods in the following Test examples 1 and 2.

<Test Method> Test Example 1 Test of Harmful Substance Eliminating Capability

A Hamburg II automatic smoking device was made to smoke, 10 times in total, each mainstream smoke (air: cigarette=7:3) of the 4 kinds of the cigarettes prepared as described above in 1 puff/35 ml/2 sec. by 20 pieces/day. Thereafter, the amount of benzpyrene contained in the total gases exhausted was measured. The result is shown in FIG. 1 and Table 1.

TABLE 1 Outlet flow of benzpyrene Average concentration of benzpyrene in mainstream smoke Cigarette filter for test (ng/cig) Acetate filter + DNA-attached 10.6 corn cob powder Acetate filter + Corn cob 12.0 powder Acetate filter + Active carbon 15.2 Acetate filter alone 23.0

As shown in FIG. 1 and Table 1, regarding the cigarette filter using DNA-attached corn cob powder, the average concentration of benzpyrene in mainstream smoke decreases by about 54% compared with the case of acetate filter alone, and it decreases by about 30% compared with active carbon, and about 12% compared with corn cob powder alone, which made it clear to have a high adsorbing/eliminating effect on benzpyrene.

Test Example 2 Test of Smoking Feeling

The four kinds of cigarettes for test prepared in the above procedure were smoked by 30 subjects, and the results were compared in the viewpoints of flavor and suction feeling for one that DNA-attached corn cob powder was added, one that only corn cob powder was added, one that an active carbon was added, and acetate filter alone.

Evaluations were carried out by checking how much flavor and suction feeling were lowered in comparison with acetate filter alone for one that DNA-attached corn cob powder was added, one that corn cob powder was added and one that an active carbon was added thereby to each calculate the average points:

Not changed, or not perceived at all . . . 3 points Somewhat uncomfortable feeling . . . 2 points Clearly uncomfortable feeling . . . 1 point

The result is shown in Table 2

TABLE 2 Cigarette filter for test Flavor Suction feeling Acetate filter + DNA-attached corn cob 2.7 2.8 powder Acetate filter + Corn cob powder 2.7 2.8 Acetate filter + Active carbon 2.7 2.8

As shown in Table 2, regarding the cigarette filter using DNA-attached corn cob powder, the results of flavor characteristic of cigarette and suction feeling were the almost same as the case of acetate filter alone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the detected amount of benzpyrene in mainstream smoke in different cigarette filters for test. 

1. A cigarette filter containing a harmful substance-eliminating material comprising a corn cob powder or a corn cob powder and a double-stranded DNA.
 2. The cigarette filter according to claim 1, wherein said double-stranded DNA is attached onto the external surface of said corn cob powder.
 3. The cigarette filter according to claim 1, wherein said corn cob powder is dried to contain a water content of 5 mass % or less.
 4. The cigarette filter according to claim 1, wherein said harmful substance-eliminating material is mixed in a filter rod consisting of a fibrous filter material.
 5. The cigarette filter according to claim 4, wherein said harmful substance-eliminating material comprises said double-stranded DNA and/or a corn cob powder having a particle diameter of 150 μm to 500 μm.
 6. The cigarette filter according to claim 1, wherein a plurality of filter rods consisting of a fibrous filter material are provided, and a layer composed of said harmful substance-eliminating material is interposed between said filter rods.
 7. The cigarette filter according to claim 6, wherein said harmful substance-eliminating material comprises said double-stranded DNA and/or a corn cob powder having a particle diameter of 500 μm to 1000 μm.
 8. The cigarette filter according to claim 1, wherein said harmful substance is dioxins or/and benzpyrene. 